There are known in the prior art several types of insulating cementitious building blocks such as those disclosed in U.S. Pat. Nos. 4,185,434; 4,551,959; 4,856,248; 4,986,049 and 5,066,440.
In U.S. Pat. No. 4,185,434 (Jones) the building block is formed from two block parts, one including the front wall of the block and one including the rear wall of the block. These two parts are maintained spaced apart by a layer of insulating material. There are internal "A" and smaller end cavities "B" in Jones' invention that are positioned so that when a plurality of blocks are placed in juxtaposition with each other to form a wall, the overall dimensions of adjacent cavities B are about the same as the dimensions of the cavities A. The cavities, corners and sections 4 and 5 all have squared or linear configurations which could cause the easy fracturing of the cementitious block when a strain is exerted thereon. Also, Jones' block does not have the appearance or feel of a conventional block and could present an unaccustomed structure for the mason to work with. In addition, main sections 4 and 5 are approximately the same size which could prevent obtaining maximum insulation properties as will later be explained.
In Schmid, U.S. Pat. No. 4,551,959, an insulating building block is described having two spaced supportive parts separated from one another by an insulating material. The block of Schmid is substantially solid with no griping holes or means for the mason or builder to work with when lifting and placing the block in position. In addition, the supportive parts 12 and 14 are substantially the same in size and configuration (column 3 lines 29-31). As above noted, maximum insulation properties are not provided when the inner or inside section of the block is the same size or smaller size than the outside section of the block. When the inside section has a larger mass or is of a greater size than the outside section, a significant improvement in insulating properties of the block can be realized. Also in Schmid, his projections 58 and 60 are smaller than the openings of the recesses surrounding these projections so that if the insulation 16 erodes away, sections 12 and 14 will easily separate and fall from each other.
In U.S. Pat. No. 4,856,248 (Larson) a building element or block is described having linear sections of varied densities. All sections of Larson are squared or have a linear configuration which could cause easy fracturing of portions of the block. Also, there are no grip holes in Larson's structure which would make it difficult for the mason to lift or place the blocks in position. Also, the sections of Larson identified by walls 80-82 and 90-92 are approximately the same size which does not provide maximum insulating properties of the block or building element.
In U.S. Pat. Nos. 4,986,049 and 5,066,440 (Kennedy et al) an improved building block is described having main sections 12 and 14 interlocked by T-shaped structures 34 and 36. Main sections 12 and 14 are approximately equal in size and do not provide any griping holes therein. Insulating portion 16 has thumb holes 154 which are intended to facilitate lifting of the blocks. Conventional cement masonry blocks have substantially large griping holes which workers are accustomed to using. Also, these conventional large griping holes, in addition to facilitating lifting, also provide convenient conduits for accommodating wiring and providing an opening or openings for re-bars that are used to reinforce walls. Therefore, the absence of griping holes and the equal mass of inside and outside sections 12 and 14 are important drawbacks to Kennedy et al's structure.
Also, as suggested in the prior art, breaking away a portion of a block to accommodate re-bar or to provide space for reinforcing rods is cumbersome and could cause block fracturing. Fracturing of the block obviously would compromise the integrity and strength of the wall.